Use of sensors for noise suppression in a mobile communication device

ABSTRACT

Techniques are described herein that use sensors (e.g., microphones) for noise reduction in a mobile communication device. For example, one technique enables a first sensor that is initially configured to be a speech sensor to be used as a noise reference sensor. This technique also enables a second sensor that is initially configured to be a noise reference sensor to be used as a speech sensor. Another technique enables a primary sensor and/or a secondary sensor in a handset of a mobile communication device to be used as a speech sensor while a sensor in a headset of the mobile communication device is used as a noise reference sensor, or vice versa. In yet another technique, a secondary sensor in a mobile communication device is configured to be a directional sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/151,977, now allowed, filed Jun. 2, 2011, which claims the benefit ofU.S. Provisional Application No. 61/434,280, filed Jan. 19, 2011, theentireties of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention generally relates to noise suppression.

Background

Headphones and headsets (referred to collectively hereinafter as“headsets”) that include noise reduction functionality are intended toprovide greater speech and/or music quality in noisy environments. Suchheadsets (referred to hereinafter as “noise reduction headsets”) may beused in conjunction with telephones (e.g., cellular phones, landlinephones, or voice-over-internet-protocol (VoIP) phones), computerdictation devices, portable music players, etc. For example, theheadsets may be used during air travel to listen to music or for makingphone calls while driving. When the headsets are used, any microphonesthat are included in the underlying devices to which the headsets areattached traditionally are disabled.

Noise reduction headsets that are used for purposes of communicationoften include a primary microphone (a.k.a. a speech microphone) fordetecting speech of a user and a secondary microphone (a.k.a. a noisereference microphone) for detecting noise that may interfere withaccuracy of the detected speech. A signal that is received by theprimary microphone is referred to as a primary signal. In practice, theprimary signal usually includes a speech component (e.g., a user'sspeech) and a noise component (e.g., background noise). A signal that isreceived by the secondary sensor is referred to as a secondary signal.The secondary signal usually includes reference noise (e.g., backgroundnoise), which may be combined with the primary signal to provide aspeech signal that has a reduced noise component, as compared to theprimary signal.

More recently, mobile communication device handsets have been developedthat include noise reduction functionality. Such handsets often includea primary microphone and a secondary microphone that function asdescribed above with reference to noise reduction headsets. However, anymicrophones that are included in the handsets traditionally are disabledwhen headsets are used in conjunction with the handsets.

The relatively close proximity of a primary microphone and a secondarymicrophone in either a handset or a headset may result in distortion ofa speech signal upon performance of a noise reduction operation. Forexample, the primary signal may include some aspects of reference noise,and/or the secondary signal may include some aspects of the speechsignal. In accordance with this example, performance of the noisereduction operation may remove a portion of a speech component of thespeech signal. Also, incorporating noise reduction functionality (e.g.,a secondary microphone, other hardware, and/or software) into a headsetoften increases complexity and/or cost of the headset.

BRIEF SUMMARY OF THE INVENTION

A system and/or method for using sensors (e.g., microphones) for noisereduction in a mobile communication device, substantially as shown inand/or described in connection with at least one of the figures, as setforth more completely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate embodiments of the present inventionand, together with the description, further serve to explain theprinciples involved and to enable a person skilled in the relevantart(s) to make and use the disclosed technologies.

FIGS. 1A, 1B, and 1C depict respective front, back, and side views of anexample handset of a mobile communication device in accordance withembodiments described herein.

FIG. 2 is a block diagram of an example mobile communication device thatincludes a handset and a headset in accordance with an embodimentdescribed herein.

FIGS. 3-7 show example configurations of a handset of a mobilecommunication device in accordance with embodiments described herein.

FIG. 8 depicts a flowchart of an example method for using sensors fornoise reduction in a mobile communication device in accordance with anembodiment described herein.

The features and advantages of the disclosed technologies will becomemore apparent from the detailed description set forth below when takenin conjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements. The drawing in which an elementfirst appears is indicated by the leftmost digit(s) in the correspondingreference number.

DETAILED DESCRIPTION OF THE INVENTION I. Introduction

The following detailed description refers to the accompanying drawingsthat illustrate example embodiments of the present invention. However,the scope of the present invention is not limited to these embodiments,but is instead defined by the appended claims. Thus, embodiments beyondthose shown in the accompanying drawings, such as modified versions ofthe illustrated embodiments, may nevertheless be encompassed by thepresent invention.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” or the like, indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Furthermore, whena particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to implement such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described.

Various approaches are described herein for, among other things, usingsensors (e.g., microphones) for noise reduction in a mobilecommunication device. The noise reduction techniques described hereinuse such sensors in ways that are not contemplated by conventional noisereduction techniques. For example, one approach enables a first sensorthat is initially configured to be a speech sensor to be used as a noisereference sensor. This approach also enables a second sensor that isinitially configured to be a noise reference sensor to be used as aspeech sensor. Another approach enables a primary sensor and/or asecondary sensor in a handset of a mobile communication device to beused as a speech sensor while a sensor in a headset of the mobilecommunication device is used as a noise reference sensor. Yet anotherapproach enables a primary sensor and/or a secondary sensor in a handsetof a mobile communication device to be used as a noise reference sensorwhile a sensor in a headset of the mobile communication device is usedas a speech sensor. In still another approach, a secondary sensor in amobile communication device is configured to be a directional sensor.

An example mobile communication device is described that includes aheadset and a handset. The headset includes a first sensor configured todetect a first audio signal for a first duration that includes adesignated time period. The handset is communicatively coupled to theheadset. The handset includes second sensor(s) and a processor. Thesecond sensor(s) are configured to detect a second audio signal for asecond duration that includes the designated time period. The processoris configured to compare a portion (e.g., all or less than all) of arepresentation of the first audio signal that corresponds to thedesignated time period and a portion (e.g., all or less than all) of arepresentation of the second audio signal that corresponds to thedesignated time period to determine a noise-reduced signal. Therepresentation of the first audio signal may be unchanged from the firstaudio signal that is detected by the first sensor. Alternatively, therepresentation of the first audio signal may be a modified (e.g.,filtered) version of the first audio signal that is detected by thefirst sensor. The representation of the second audio signal may beunchanged from the second audio signal that is detected by the secondsensor(s). Alternatively, the representation of the second audio signalmay be a modified (e.g., filtered) version of the second audio signalthat is detected by the second sensor(s). The noise-reduced signalrepresents a difference between the portion of the representation of thefirst audio signal and the portion of the representation of the secondaudio signal.

An example handset of a mobile communication device is described. Thehandset includes a first sensor, a second sensor, and a processor. Thefirst sensor is configured to be proximate a mouth of a user duringoperation of the handset by the user. The second sensor is configured tobe distal the mouth of the user during the operation of the handset bythe user. The processor is configured to switch the first sensor and thesecond sensor between a first mode of operation and a second mode ofoperation. The first mode is characterized by the first sensor beingconfigured as a primary sensor to detect a first primary signal thatrepresents speech of the user. The first mode is further characterizedby the second sensor being configured as a secondary sensor to detect afirst secondary signal that represents reference noise. The second modeis characterized by the first sensor being configured as a secondarysensor to detect a second secondary signal that represents referencenoise. The second mode is further characterized by the second sensorbeing configured as a primary sensor to detect a second primary signalthat represents sound from a targeted noise source. The processor isconfigured to subtract a representation of the first secondary signalfrom a representation of the first primary signal to provide anoise-reduced first primary signal in response to the first sensor andthe second sensor being switched from the second mode to the first mode.The processor is configured to subtract a representation of the secondsecondary signal from a representation of the second primary signal toprovide a noise-reduced second primary signal in response to the firstsensor and the second sensor being switched from the first mode to thesecond mode. The representations of the first primary signal, firstsecondary signal, second primary signal, and/or second secondary signalmay be changed or unchanged from the respective first primary signal,first secondary signal, second primary signal, and/or second secondarysignal as detected by the sensor(s).

Another example handset of a mobile communication device is described.The handset includes a first sensor, a second sensor, and a processor.The first sensor is configured to be distal a mouth of a user duringoperation of the handset by the user. The first sensor is furtherconfigured to detect a first audio signal for a first duration thatincludes a designated time period. The first sensor is a directionalsensor that emphasizes sound received from a specified direction morethan sound received from directions other than the specified direction.The second sensor is configured to be proximate the mouth of the userduring operation of the handset by the user. The second sensor isfurther configured to detect a second audio signal for a second durationthat includes the designated time period. The processor is configured tocompare a portion (e.g., all or less than all) of a representation ofthe first audio signal that corresponds to the designated time periodand a portion (e.g., all or less than all) of a representation of thesecond audio signal that corresponds to the designated time period todetermine a noise-reduced signal. The representation of the first audiosignal may be changed or unchanged from the first audio signal that isdetected by the first sensor. The representation of the second audiosignal may be changed or unchanged from the second audio signal that isdetected by the second sensor. The noise-reduced signal represents adifference between the portion of the representation of the first audiosignal and the portion of the representation of the second audio signal.

An example method is described for reducing noise in a mobilecommunication device that has first and second opposing surfaces. Inaccordance with this example method, an image of a targeted object iscaptured using a camera that is configured on the first surface. A firstaudio signal from a first sensor that is configured on the first surfaceand a second audio signal from a second sensor that is configured on asurface of the mobile communication device other than the first surfaceare received contemporaneously. The first audio signal represents soundprovided by the targeted object. The second audio signal representssound provided by objects other than the targeted object. The image ofthe targeted object is displayed using a display that is configured onthe second surface. A representation of the second audio signal issubtracted from a representation of the first audio signal to provide anoise-reduced representation of the first audio signal. Therepresentation of the first audio signal may be changed or unchangedfrom the first audio signal that is received from the first sensor. Therepresentation of the second audio signal may be changed or unchangedfrom the second audio signal that is received from the second sensor.

The noise reduction techniques described herein have a variety ofbenefits as compared to conventional noise reduction techniques. Forinstance, the techniques described herein may reduce distortion of aprimary or speech signal and/or reduce noise (e.g., background noise,babble noise, etc.) that is associated with the primary or speech signalmore than conventional techniques. The techniques described herein mayincrease accuracy of voice activity detection (VAD), especially inrelatively noisy environments. A handset of a mobile communicationdevice may be placed in relatively close proximity to a noise source fordetection of reference noise, and a headset (e.g., wireless headset) ofthe mobile communication device may be placed in relatively closeproximity to a speech source (e.g., a user's mouth) for detection ofspeech. The techniques described herein may utilize any (e.g., all) ofthe sensors that are included in a mobile communication device forreducing noise.

II. Example Noise Reduction Embodiments

FIGS. 1A, 1B, and 1C depict respective front, back, and side views of anexample handset 100 of a mobile communication device in accordance withembodiments described herein. For example, mobile communication device100 may be a personal digital assistant, (PDA), a cellular telephone, atablet computer, etc. As shown in FIG. 1A, a front portion of mobilecommunication device 100 includes a display 102 and a first sensor 106(e.g., a first microphone). Display 102 is configured to display imagesto a user of mobile communication device 100. First sensor 106 ispositioned to be proximate the user's mouth during regular use of mobilecommunication device 100. Accordingly, first sensor 106 is positioned todetect the user's speech. It can therefore be said that first sensor 106is configured as a primary sensor during regular use of mobilecommunication device 100, though first sensor 106 may be configured as asecondary sensor for detecting reference noise in accordance with someexample embodiments.

As shown in FIG. 1B, a back portion of mobile communication device 100includes a camera 108 and a second sensor 110 (e.g., a secondmicrophone). Camera 108 is configured to capture images. For example,such images may be displayed to the user by display 102. Second sensor110 is positioned to be farther from the user's mouth during regular usethan first sensor 106. For instance, second sensor 110 may be positionedas far from the user's mount during regular use as possible. It cantherefore be said that second sensor 110 is configured as a secondarysensor during regular use of mobile communication device 100, thoughsecond sensor 110 may be configured as a primary sensor for detectingsound from a targeted object in accordance with some exampleembodiments.

By positioning first sensor 106 so that it is closer to the user's mouththan second sensor 110 during regular use, a magnitude of the user'sspeech that is detected by first sensor 106 is likely to be greater thana magnitude of the user's speech that is detected by second sensor 110.Furthermore, a magnitude of background noise that is detected by firstsensor 106 is likely to be less than a magnitude of the background noisethat is detected by second sensor 110.

As shown in FIG. 1C, mobile communication device 100 has a first surface112 and a second surface 114. First and second surfaces 112 and 114 areshown in FIG. 1C to be opposing surfaces for illustrative purpose andare not intended to be limiting. For instance, first and second surfacesneed not necessarily be opposing surfaces. Display 102 and first sensor106 are shown to be configured on the first surface 112. Camera 108 andsecond sensor 110 are shown to be configured on the second surface 114.It will be recognized that mobile communication device 100 need notnecessarily include display 102, camera 108, and/or second sensor 110.

Mobile communication device 100 includes a processor 104 that isconfigured to process audio signals, such as a first audio signal thatis detected by first sensor 106, a second audio signal that is detectedby second sensor 110, etc. to provide a noise-reduced representation ofan audio signal. For example, the noise-reduced representation of theaudio signal may be a noise-reduced representation of the first audiosignal. In accordance with this example, processor 104 may subtract arepresentation of the second audio signal or a representation of anotheraudio signal from a representation of the first audio signal to providethe noise-reduced representation of the first audio signal. In anotherexample, the noise-reduced representation of the audio signal may be anoise-reduced representation of the second audio signal. In accordancewith this example, processor 104 may subtract a representation of thefirst audio signal or a representation of another audio signal from arepresentation of the second audio signal to provide the noise-reducedrepresentation of the second audio signal.

Second sensor 110 is shown in FIG. 1C to be configured as a directionalsensor for illustrative purposes and is not intended to be limiting. Adirectional sensor is a sensor that emphasizes sound received from aspecified direction more than sound received from directions other thanthe specified direction. For example, second sensor 110 may beconfigured to emphasize sound received from direction D, which isdefined by angle α, more than sound received from directions other thandirection D. In accordance with this example, direction D may correspondto a figurative line that bisects angle α. It will be recognized thatsecond sensor 110 need not necessarily be a directional sensor. Forinstance, second sensor 110 may be an omni-directional sensor.

In accordance with an example embodiment, first sensor 106 is configuredto detect a first audio signal for a first duration that includes adesignated time period. Second sensor 110 is configured to detect asecond audio signal for a second duration that includes the designatedtime period. In accordance with this embodiment, second sensor 110 is adirectional sensor that emphasizes sound received from a specifieddirection more than sound received from directions other than thespecified direction. Processor 104 is configured to compare a portion(e.g., all or less than all) of a representation of the first audiosignal that corresponds to the designated time period and a portion(e.g., all or less than all) of a representation of the second audiosignal that corresponds to the designated time period to determine anoise-reduced signal. The representation of the first audio signal maybe unchanged from the first audio signal that is detected by firstsensor 106. Alternatively, the representation of the first audio signalmay be a modified (e.g., filtered) version of the first audio signalthat is detected by first sensor 106. For instance, processor 104 maymodify the first audio signal to provide the representation of the firstaudio signal. The representation of the second audio signal may beunchanged from the second audio signal that is detected by second sensor110. Alternatively, the representation of the second audio signal may bea modified (e.g., filtered) version of the second audio signal that isdetected by second sensor 110. For instance, processor 104 may modifythe second audio signal to provide the representation of the secondaudio signal. The noise-reduced signal represents a difference betweenthe portion of the representation of the first audio signal and theportion of the representation of the second audio signal.

In an aspect of the aforementioned embodiment, the first audio signalrepresents sound provided by the user. The second audio signalrepresents sound that is provided by a targeted noise source and that isreceived by second sensor 110 from the specified direction. Processor104 is configured to subtract the portion of the representation of thesecond audio signal from the portion of the representation of the firstaudio signal to provide the noise-reduced signal.

In another aspect of the aforementioned embodiment, camera 108 isconfigured to capture an image of a targeted object. The first audiosignal represents sound provided by objects other than the targetedobject. The second audio signal represents sound that is provided by thetargeted object and that is received by second sensor 110 from thespecified direction. Processor 104 is configured to subtract the portionof the representation of the first audio signal from the portion of therepresentation of the second audio signal to provide the noise-reducedsignal. For instance, processor 104 may subtract the portion of therepresentation of the first audio signal from the portion of therepresentation of the second audio signal to provide the noise-reducedsignal in response to activation of camera 108 (e.g., in response tocamera 108 being switched from an “off” state to an “on” state).

In yet another aspect of the aforementioned embodiment, second sensor110 is an adaptable directional sensor. An adaptable directional sensoris a directional sensor having a specified direction that is adjustable.Processor 104 is configured to determine a location of an audio sourcebased on sounds that are received by second sensor 110. Second sensor110 is configured to set the specified direction to correspond to thelocation of the audio source.

First sensor 106 and second sensor 110 are shown to be positioned on therespective front and back portions of mobile communication device 100(e.g., configured on the respective first and second surfaces 112 and114) in FIGS. 1A, 1B, and 1C for illustrative purposes and are notintended to be limiting. Persons skilled in the relevant art(s) willrecognize that first sensor 106 and second sensor 110 may be positionedin any suitable locations on mobile communication device 100. Forexample, first sensor 106 may be configured on a bottom surface or aside surface of mobile communication device 100. In another example,second sensor 110 may be configured on a top surface or a side surfaceof mobile communication device 100. Nevertheless, the effectiveness ofsome techniques described herein may be improved if first sensor 106 andsecond sensor 110 are positioned on mobile communication device 100 suchthat first sensor 106 is closer to a targeted audio source (e.g., theuser's mouth during regular use of mobile communication device 100) thansecond sensor 110. The effectiveness of other techniques describedherein may be improved if first sensor 106 and second sensor 110 arepositioned on mobile communication device 100 such that second sensor110 is closer to a targeted audio source (e.g., an object of whichcamera 108 captures image(s)) than first sensor 106.

One first sensor 106 is shown in FIGS. 1A and 1C for illustrativepurposes and is not intended to be limiting. It will be recognized thatmobile communication device 100 may include any number of primarysensors. One second sensor 110 is shown in FIGS. 1B and 1C forillustrative purposes and is not intended to be limiting. It will berecognized that mobile communication device 100 may include any numberof secondary sensors.

In accordance with an embodiment, processor 104 is configured to switchfirst sensor 106 and second sensor 110 between a first mode of operationand a second mode of operation. The first mode is characterized by firstsensor 106 being configured as a primary sensor to detect a firstprimary signal that represents speech of the user. The first mode isfurther characterized by second sensor 110 being configured as asecondary sensor to detect a first secondary signal that representsreference noise. The second mode is characterized by first sensor 106being configured as a secondary sensor to detect a second secondarysignal that represents reference noise. The second mode is furthercharacterized by second sensor 110 being configured as a primary sensorto detect a second primary signal that represents sound from a targetednoise source. Processor 104 is configured to subtract a representationof the first secondary signal from a representation of the first primarysignal to provide a noise-reduced first primary signal in response tofirst sensor 106 and second sensor 110 being switched from the secondmode to the first mode. Processor 104 is configured to subtract arepresentation of the second secondary signal from a representation ofthe second primary signal to provide a noise-reduced second primarysignal in response to first sensor 106 and second sensor 110 beingswitched from the first mode to the second mode.

In an aspect of the aforementioned embodiment, the first mode is furthercharacterized by camera 108 being configured in an off state. The secondmode is further characterized by camera 108 being configured in an onstate to capture an image of the targeted noise source

FIG. 2 is a block diagram of an example mobile communication device 200that includes a handset 220 and a headset 230 in accordance with anembodiment described herein. As shown in FIG. 2, handset 220 and headset230 are communicatively coupled via a connection 222. Connection 222 maybe any suitable type of connection, such as a wireless (e.g.,Bluetooth®) connection, a wired connection, etc.

Handset 220 includes a display 202, a processor 204, a first sensor 206,and a second sensor 210, which operate similarly to display 102,processor 104, first sensor 106, and second sensor 110, respectively, asdescribed above with reference to FIGS. 1A, 1B, and 1C. It will beapparent to persons skilled in the relevant art(s) that handset 220 neednot necessarily include second sensor 210. Handset 220 is shown in FIG.2 to further include a first transceiver 216. First transceiver 216 isconfigured to provide representations of audio signals that are detectedby first sensor 206 and/or second sensor 210 to headset 230 viaconnection 222. It will be recognized that processor 204 may process(e.g., digitize, filter, amplify, etc.) such audio signals to provide(e.g., generate) the aforementioned representations of the audio signalsfor provision by first transceiver 216. First transceiver 216 is furtherconfigured to receive representations of audio signals that are detectedby third sensor 224 of headset 230. Third sensor 224 is described infurther detail below.

Headset 230 includes third sensor 224 and a second transceiver 218.Third sensor is configured to detect audio signals. Third sensor 224 maybe configured to be a primary sensor or a secondary sensor. For example,if headset 230 is positioned relatively near (e.g., proximate) atargeted audio source, such as the mouth of a user who is wearingheadset 230, third sensor 230 is said to be configured as a primarysensor. In another example, if headset 230 is positioned relatively farfrom the targeted audio source, third sensor 230 is said to beconfigured as a secondary sensor.

Second transceiver 218 is configured to provide representations of audiosignals that are detected by third sensor 224 to handset 220 viaconnection 222. It will be recognized that headset 230 may include aprocessor (not shown) for processing (e.g., digitizing, filtering,amplifying, etc.) such audio signals to provide (e.g., generate) theaforementioned audio signals for provision by second transceiver 218.Second transceiver 218 is further configured to receive representationsof audio signals that are detected by first sensor 206 and/or secondsensor 210 of handset 220.

In accordance with an example embodiment, third sensor 224 is configuredto detect a first audio signal for a first duration that includes adesignated time period. First sensor 206 and/or second sensor 210 isconfigured to detect a second audio signal for a second duration thatincludes the designated time period. Processor 204 is configured tocompare a portion (e.g., all or less than all) of a representation ofthe first audio signal that corresponds to the designated time periodand a portion (e.g., all or less than all) of a representation of thesecond audio signal that corresponds to the designated time period todetermine a noise-reduced signal, which represents a difference betweenthe portion of the representation of the first audio signal and theportion of the representation of the second audio signal. Therepresentation of the first audio signal may be unchanged from the firstaudio signal that is detected by third sensor 224. Alternatively, therepresentation of the first audio signal may be a modified (e.g.,filtered) version of the first audio signal that is detected by thirdsensor 224. For instance, processor 204 may modify the first audiosignal to provide the representation of the first audio signal. Therepresentation of the second audio signal may be unchanged from thesecond audio signal that is detected by first sensor 206 and/or secondsensor 210. Alternatively, the representation of the second audio signalmay be a modified (e.g., filtered) version of the second audio signalthat is detected by first sensor 206 and/or second sensor 210. Forinstance, processor 204 may modify the second audio signal to providethe representation of the second audio signal.

In an aspect of the aforementioned embodiment, the first audio signalmay represent sound provided by a targeted audio source. The targetedaudio source may be a user of mobile communication device 200, forexample. The second audio signal represents sound provided by audiosources other than the targeted audio source. Processor 204 may beconfigured to subtract the portion of the representation of the secondaudio signal from the portion of the representation of the first audiosignal to provide the noise-reduced signal.

In accordance with this aspect, processor 204 may be further configuredto determine whether a fidelity of the noise-reduced signal is less thana fidelity threshold. For example, the fidelity of the noise-reducedsignal may correspond to a signal-to-noise ratio (SNR) of thenoise-reduced signal. In another example, the fidelity threshold maycorrespond to a fidelity of the first audio signal. Processor 204 may befurther configured to switch from providing the noise-reduced signal asan output signal to providing the first audio signal (e.g., areconstruction of the first audio signal) as the output signal in amanner that is imperceptible by a user of the mobile communicationdevice in response to the fidelity of the noise-reduced signal beingless than the fidelity threshold. For instance, processor 204 maydisable second sensor 210 in response to the fidelity of thenoise-reduced signal being less than the fidelity threshold.

In another aspect of the aforementioned embodiment, the second audiosignal may represent sound provided by a targeted audio source. Thefirst audio signal may represent sound provided by audio sources otherthan the targeted audio source. Processor 204 may be configured tosubtract the portion of the representation of the first audio signalfrom the portion of the representation of the second audio signal toprovide the noise-reduced signal.

In accordance with this aspect, processor 204 may be further configuredto determine whether a fidelity of the noise-reduced signal is less thana fidelity threshold. For example, the fidelity of the noise-reducedsignal may correspond to a signal-to-noise ratio (SNR) of thenoise-reduced signal. In another example, the fidelity threshold maycorrespond to a fidelity of the second audio signal. Processor 204 maybe further configured to switch from providing the noise-reduced signalas an output signal to providing the second audio signal (e.g., areconstruction of the second audio signal) as the output signal in amanner that is imperceptible by a user of the mobile communicationdevice in response to the fidelity of the noise-reduced signal beingless than the fidelity threshold. For instance, processor 204 maydisable first sensor 206 in response to the fidelity of thenoise-reduced signal being less than the fidelity threshold.

In yet another aspect of the aforementioned embodiment, multiple sensors(e.g., first sensor 206, second sensor 210, and/or other sensor(s)) inhandset 220 may collaboratively detect the second audio signal. Suchsensors may be configured on any suitable surfaces (e.g., any ofsurfaces 212, 214, 226, and/or 228) of handset 220. In FIG. 2, surfaces212 and 214 are shown to be opposing surfaces, and surfaces 226 and 228are shown to be opposing surfaces, for illustrative purposes and are notintended to be limiting. Each of surfaces 212 and 214 is said to beadjacent to surfaces 226 and 228. Each of surfaces 226 and 228 is saidto be adjacent to surfaces 212 and 214. Each of the sensors in handset220 may be any suitable type of sensor, including but not limited to adirectional sensor (e.g., an adaptable directional sensor), a digitalsensor, an analog sensor, etc.

FIGS. 3-7 show example configurations 300, 400, 500, and 600 of ahandset of a mobile communication device in accordance with embodimentsdescribed herein. As shown in FIG. 3, configuration 300 includes aprocessor 304, a sensor 306, a switch 334, and a headset connector 336.Sensor 306 is configured to detect audio signals. Headset connector 336is configured to receive a headset plug that is connected to a wiredheadset, thereby enabling representations of audio signals that aredetected by the headset to be transferred from the headset to thehandset for processing by processor 304. Processor 304 is shown to havea first sensor input element 332A and a second sensor input element332B. Processor 304 processes (e.g., digitizes, amplifies, filters,etc.) audio signals that are received at first sensor input element332A. Switch 334 is configured to switch between a first state and asecond state. In the first state, switch 334 connects first sensor inputelement 332A to sensor 306 but not to headset connector 336. In thesecond state, switch 334 connects first sensor input element 332A toheadset connector 336 but not to sensor 306. Accordingly, switch 334switches to the first state in response to no headset plug beinginserted into headset connector 336. Switch 334 switches to the secondstate in response to a headset plug being inserted into headsetconnector 336. Second sensor input element 532B is not used.

As shown in FIG. 4, configuration 400 includes a processor 404, a sensor406, and a headset connector 436, which operate similarly to processor304, sensor 306, and headset connector 336, respectively, as describedabove with reference to FIG. 3. However, configuration 400 differs fromconfiguration 300 of FIG. 3 in that sensor 406 is coupled to firstsensor input element 432A, and headset connector 436 is coupled tosecond sensor input element 432B. Processor 404 processes audio signalsthat are received at first sensor input element 432A and audio signalsthat are received at second sensor input element 432B. For instance,processor 404 may compare representations of the audio signals that arereceived at first sensor input element 432A and representations of theaudio signals that are received at second sensor input element 432B toprovide noise-reduced audio signals. The representations of the audiosignals that are received at first sensor input element 432A may beunchanged from the audio signals that are received at first sensor inputelement 432A. Alternatively, the representations of the audio signalsthat are received at first sensor input element 432A may be modified(e.g., filtered) versions of the audio signals that are received atfirst sensor input element 432A. For instance, processor 404 may modifythe audio signals that are received at first sensor input element 432Ato provide the representations of the audio signals that are received atfirst sensor input element 432A. The representations of the audiosignals that are received at second sensor input element 432B may beunchanged from the audio signals that are received at second sensorinput element 432B. Alternatively, the representations of the audiosignals that are received at second sensor input element 432B may bemodified (e.g., filtered) versions of the audio signals that arereceived at second sensor input element 432B. For instance, processor404 may modify the audio signals that are received at second sensorinput element 432B to provide the representations of the audio signalsthat are received at second sensor input element 432B.

In an example embodiment, the handset, as depicted by configuration 400,is used for an audio event (e.g., a voice call), and a headset that isconnected to the handset via headset connector 406 is used to detectreference noise. In accordance with this embodiment, processor 404subtracts representations of the audio signals that are received fromthe headset via headset connector 436 from representations of the audiosignals that are received from microphone 406 to provide thenoise-reduced audio signals.

In another example embodiment, a headset that is connected to headsetconnector 436 is used for an audio event (e.g., a voice call), andmicrophone 406 is used to detect reference noise. In accordance withthis embodiment, processor 404 subtracts the representations of theaudio signals that are received from microphone 406 from therepresentations of the audio signals that are received from the headsetvia headset connector 436 to provide the noise-reduced audio signals.

As shown in FIG. 5, configuration 500 includes a processor 504, a sensor506, a switch 534, and a headset connector 536, which operate similarlyto processor 304, sensor 306, switch 334, and headset connector 336, asdescribed above with reference to FIG. 3. However, configuration 500differs from configuration 300 of FIG. 3 in that processor 500 has asingle sensor input element 532, and switch 534 is capable of switchingbetween the first state, the second state, and a third state thatcorresponds to a wireless headset mode of operation. In the third state,switch 534 connects sensor input element 532 to neither sensor 506 norheadset connector 536. For instance, switch 534 may connect sensor inputelement 532 to a fixed potential (e.g., ground potential 538) inaccordance with the third state, as shown in FIG. 5. Accordingly, switch534 switches to the third state in response to initiation of thewireless headset mode of operation, regardless whether a headset plug isinserted into headset connector 536.

As shown in FIG. 6, configuration 600 includes a processor 604, a sensor606, and a headset connector 636, which operate similarly to processor304, sensor 306, and headset connector 336, respectively, as describedabove with reference to FIG. 3. Configuration 600 differs fromconfiguration 500 of FIG. 5 in that switch 634 does not switch to thethird state in response to initiation of the wireless headset mode ofoperation. For instance, switch 634 is capable of being in the firststate or the second state during the wireless headset mode of operation.As shown in FIG. 6, wireless headset 630 is wirelessly connected to thehandset, as depicted by configuration 600, via a wireless connection622, simultaneously with sensor input element 632 being connected tomicrophone 606 or headset connector 636 via switch 634.

In an example embodiment, wireless headset 630 is used for an audioevent (e.g., a voice call), and microphone 606 or a headset that isconnected to headset connector 636 is used to detect reference noise. Inaccordance with this embodiment, processor 604 subtracts representationsof the audio signals that are received from microphone 606 or theheadset that is connected to headset connector 636 from representationsof the audio signals that are received from wireless headset 630 toprovide noise-reduced audio signals.

As shown in FIG. 7, configuration 700 includes a processor 704, a firstsensor 706, a switch 734, and a headset connector 736, which operatesimilarly to processor 304, sensor 306, switch 334, and headsetconnector 336, as described above with reference to FIG. 3. However,configuration 700 differs from configuration 300 of FIG. 3 in thatconfiguration 700 includes a second sensor 740, which is coupled tosecond sensor input element 732B. Processor 704 processes audio signalsthat are received at first sensor input element 732A and audio signalsthat are received at second sensor input element 732B. For instance,processor 704 may compare representations of the audio signals that arereceived at first sensor input element 732A and representations of theaudio signals that are received at second sensor input element 732B toprovide noise-reduced audio signals. The representations of the audiosignals that are received at first sensor input element 732A may beunchanged from the audio signals that are received at first sensor inputelement 732A. Alternatively, the representations of the audio signalsthat are received at first sensor input element 732A may be modified(e.g., filtered) versions of the audio signals that are received atfirst sensor input element 732A. For instance, processor 704 may modifythe audio signals that are received at first sensor input element 732Ato provide the representations of the audio signals that are received atfirst sensor input element 732A. The representations of the audiosignals that are received at second sensor input element 732B may beunchanged from the audio signals that are received at second sensorinput element 732B. Alternatively, the representations of the audiosignals that are received at second sensor input element 732B may bemodified (e.g., filtered) versions of the audio signals that arereceived at second sensor input element 732B. For instance, processor704 may modify the audio signals that are received at second sensorinput element 732B to provide the representations of the audio signalsthat are received at second sensor input element 732B.

In an example embodiment, second sensor 740 is used for an audio event(e.g., a voice call), and a headset that is connected to headsetconnector 706 is used to detect reference noise. In accordance with thisembodiment, processor 704 subtracts representations of the audio signalsthat are received from the headset via headset connector 736 fromrepresentations of the audio signals that are received from secondsensor 740 to provide the noise-reduced audio signals.

In another example embodiment, a headset that is connected to headsetconnector 736 is used for an audio event (e.g., a voice call), andsecond sensor 740 is used to detect reference noise. In accordance withthis embodiment, processor 704 subtracts the representations of theaudio signals that are received from second sensor 740 from therepresentations of the audio signals that are received from the headsetvia headset connector 736 to provide the noise-reduced audio signals. Inan aspect, switch 734 is capable of switching between coupling firstsensor input element 732A to headset connector 736 and coupling firstsensor input element 732A to first sensor 706 (e.g., on the fly) withoutdecreasing a fidelity of the noise-reduced audio signals.

FIG. 8 depicts a flowchart 800 of an example method for using sensorsfor noise reduction in a mobile communication device in accordance withan embodiment described herein. The method of flowchart 800 will now bedescribed in reference to certain elements of example mobilecommunication device 200 as described above in reference to FIG. 2.However, the method is not limited to that implementation.

As shown in FIG. 8, flowchart 800 starts at step 802. In step 802, afirst audio signal from a first sensor in a headset of a mobilecommunication device and a second audio signal from a second sensor in ahandset of the mobile communication device are receivedcontemporaneously. The headset and the handset are communicativelycoupled (e.g., via a wired or wireless connection). In an exampleimplementation, processor 204 receives the first audio signal fromsensor 224 in headset 230 contemporaneously with receiving the secondaudio signal from sensor 206 and/or sensor 210 in handset 220.

At step 804, a representation of the first audio signal and arepresentation of the second audio signal are compared to determine anoise-reduced signal that represents a difference between therepresentation of the first audio signal and the representation of thesecond audio signal. The representation of the first audio signal may beunchanged from the first audio signal that is received from the firstsensor. Alternatively, the representation of the first audio signal maybe a modified (e.g., filtered) version of the first audio signal that isreceived from the first sensor. The representation of the second audiosignal may be unchanged from the second audio signal that is receivedfrom the second sensor(s). Alternatively, the representation of thesecond audio signal may be a modified (e.g., filtered) version of thesecond audio signal that is received from the second sensor(s). In anexample implementation, processor 204 compares the representation of thefirst audio signal and the representation of the second audio signal todetermine the noise-reduced signal.

Each of processors 104, 204, 304, 404, 504, 604, and 704 is describedherein as being included in a handset of a mobile communication devicefor illustrative purposes and is not intended to be limiting. Forexample, any of processors 104, 204, 304, 404, 504, 604, and/or 704 (ora portion thereof) may be included in a headset that is communicativelycoupled to the handset. In accordance with this example, the handset mayprovide representations of audio signals that are detected by sensor(s)in the handset to the headset for processing in accordance with thenoise-reduction techniques described herein. For instance, the headsetmay compare the representations of the audio signals that are receivedfrom the handset to representations of audio signals that are detectedby sensor(s) in the headset to provide noise-reduced signals.

The invention can be put into practice using software, firmware, and/orhardware implementations other than those described herein. Anysoftware, firmware, and hardware implementations suitable for performingthe functions described herein can be used.

III. Conclusion

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. It will be understood by those skilled in the relevantart(s) that various changes in form and details may be made to theembodiments described herein without departing from the spirit and scopeof the invention as defined in the appended claims. Accordingly, thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments, but should be defined onlyin accordance with the following claims and their equivalents.

What is claimed is:
 1. A mobile communication device, comprising: afirst microphone configured to detect a first audio signal; a secondmicrophone configured to detect a second audio signal; a camera; and aprocessor configured to determine whether the camera is disabled, switchthe first microphone and the second microphone to a first mode ofoperation in response to a determination that the camera is disabled,and switch the first microphone and the second microphone to a secondmode of operation in response to a determination that the camera isenabled, wherein in the first mode: the first microphone is configuredas a primary microphone to detect a first primary signal that representsspeech of a user of the mobile communication device and the secondmicrophone is configured as a secondary microphone to detect a firstsecondary signal that represents reference noise, and wherein in thesecond mode: the first microphone is configured as the secondarymicrophone to detect a second secondary signal that represents referencenoise and the second microphone is configured as the primary microphoneto detect a second primary signal that represents sound from a targetedsource facing the camera, wherein the processor is further configuredto: subtract a representation of the first secondary signal from arepresentation of the first primary signal to provide a firstnoise-reduced primary signal in response to a determination that thecamera is disabled; and subtract a representation of the secondsecondary signal from a representation of the second primary signal toprovide a second noise-reduced primary signal in response to adetermination that the camera is enabled.
 2. The mobile communicationdevice of claim 1, wherein in the first mode: the processor is furtherconfigured to determine whether a fidelity of the first noise-reducedprimary signal is less than a first fidelity threshold and switch fromproviding the first noise-reduced primary signal as an output signal toproviding the first primary signal as the output signal in response tothe fidelity of the first noise-reduced primary signal being less thanthe first fidelity threshold; and wherein in the second mode: theprocessor is further configured to determine whether a fidelity of thesecond noise-reduced primary signal is less than a second fidelitythreshold and switch from providing the second noise-reduced primarysignal as the output signal to providing the second primary signal asthe output signal in response to the fidelity of the secondnoise-reduced primary signal being less than the second fidelitythreshold.
 3. The mobile communication device of claim 2, wherein in thefirst mode: the processor is further configured to disable the secondmicrophone in response to the fidelity of the first noise-reducedprimary signal being less than the first fidelity threshold; and whereinin the second mode: the processor is further configured to disable thefirst microphone in response to the fidelity of the second noise-reducedprimary signal being less than the second fidelity threshold.
 4. Themobile communication device of claim 2, wherein in the first mode: thefirst fidelity threshold corresponds to a fidelity of the first primarysignal; and wherein in the second mode: the second fidelity thresholdcorresponds to a fidelity of the second primary signal.
 5. The mobilecommunication device of claim 2, wherein in the first mode: the fidelityof the first noise-educed primary signal corresponds to asignal-to-noise ratio (SNR) of the first noise-reduced primary signal;and wherein in the second mode: the fidelity of the second noise-reducedprimary signal corresponds to an SNR of the second noise-reduced primarysignal.
 6. The mobile communication device of claim 1, wherein themobile communication device includes first and second opposing surfaces;wherein the first microphone is on the first surface and wherein thesecond microphone and the camera are on the second surface.
 7. A methodin a mobile communication device, comprising: receiving a first audiosignal by a first microphone of the mobile communication device;receiving a second audio signal by a second microphone of the mobilecommunication device; determining whether a camera of the mobilecommunication device is disabled; switching the first microphone and thesecond microphone to a first mode of operation in response todetermining that the camera is disabled; and switching the firstmicrophone and the second microphone to a second mode of operation inresponse to determining that the camera is enabled, wherein in the firstmode, the first microphone is configured as a primary microphone todetect a first primary signal that represents speech of a user of themobile communication device and the second microphone is configured as asecondary microphone to detect a first secondary signal that representsreference noise, and wherein in the second mode, the first microphone isconfigured as the secondary microphone to detect a second secondarysignal that represents reference noise and the second microphone isconfigured as the primary microphone to detect a second primary signalthat represents sound from a targeted source facing the camera;subtracting a representation of the first secondary signal from arepresentation of the first primary signal to provide a firstnoise-reduced primary signal in response to determining that the camerais disabled; and subtracting representation of the second secondarysignal from a representation of the second primary signal to provide asecond noise-reduced primary signal in response to determining that thecamera is enabled.
 8. The method of claim 7, further comprising:determining, in the first mode, whether a fidelity of the firstnoise-reduced primary signal is less than a first fidelity threshold andswitching from providing the first noise-reduced primary signal as anoutput signal to providing the first primary signal as the output signalin response to the fidelity of the first noise-reduced primary signalbeing less than the first fidelity threshold; and determining, in thesecond mode, whether a fidelity of the second noise-reduced primarysignal is less than a second fidelity threshold and switching fromproviding the second noise-reduced primary signal as the output signalto providing the second primary signal as the output signal in responseto the fidelity of the second noise-reduced primary signal being lessthan the second fidelity threshold.
 9. The method of claim 8, furthercomprising: disabling, in the first mode, the second microphone inresponse to the fidelity of the first noise-reduced primary signal beingless than the first fidelity threshold; and disabling, in the secondmode, the first microphone in response to the fidelity of the secondnoise-reduced primary signal being less than the second fidelitythreshold.
 10. The method of claim 8, wherein in the first mode: thefirst fidelity threshold corresponds to a fidelity of the first primarysignal; and wherein in the second mode: the second fidelity thresholdcorresponds to a fidelity of the second primary signal.
 11. The methodof claim 8, wherein in the first mode: the fidelity of the firstnoise-reduced primary signal corresponds to a signal-to-noise ratio(SNR) of the first noise-reduced primary signal; and wherein in thesecond mode: the fidelity of the second noise-reduced primary signalcorresponds to an SNR of the second noise-reduced primary signal.
 12. Amobile communication device, comprising: a first sensor configured to beproximate to a mouth of a user during operation of the mobilecommunication device by the user, a second sensor configured to bedistal to the mouth of the user during the operation of the mobilecommunication device by the user; a camera; and a processor configuredto determine whether the camera is disabled, switch the first sensor andthe second sensor to a first mode of operation in response to adetermination that the camera is disabled, and switch the first sensorand the second sensor to a second mode of operation in response to adetermination that the camera is enabled, wherein in the first mode: thefirst sensor is configured as a primary sensor to detect a first primarysignal that represents speech of the user of the mobile communicationdevice and the second sensor is configured as a secondary sensor todetect a first secondary signal that represents reference noise, andwherein in the second mode: the first sensor is configured as thesecondary sensor to detect a second secondary signal that representsreference noise and the second sensor is configured as the primarysensor to detect a second primary signal that represents sound from atargeted source facing the camera.
 13. The mobile communication deviceof claim 12, wherein the processor is further configured to: subtract arepresentation of the first secondary signal from a representation ofthe first primary signal to provide a first noise-reduced primary signalin response to a determination that the camera is disabled; and subtracta representation of the second secondary signal from a representation ofthe second primary signal to provide a second noise-reduced primarysignal in response to a determination that the camera is enabled. 14.The mobile communication device of claim 13, wherein in the first mode:the processor is further configured to determine whether a fidelity ofthe first noise-reduced primary signal is less than a first fidelitythreshold and switch from providing the first noise-reduced primarysignal as an output signal to providing the first primary signal as theoutput signal in response to the fidelity of the first noise-reducedprimary signal being less than the first fidelity threshold; and whereinin the second mode: the processor is farther configured to determinewhether a fidelity of the second noise-reduced primary signal is lessthan a second fidelity threshold and switch from providing the secondnoise-reduced primary signal as the output signal to providing thesecond primary signal as the output signal in response to the fidelityof the second noise-reduced primary signal being less than the secondfidelity threshold.
 15. The mobile communication device of claim 14,wherein in the first mode: the processor is further configured todisable the second sensor in response to the fidelity of the firstnoise-reduced primary signal being less than the first fidelitythreshold; and wherein in the second mode: the processor is furtherconfigured to disable the first sensor in response to the fidelity ofthe second noise-reduced primary signal being less than the secondfidelity threshold.
 16. The mobile communication device of claim 14,wherein in the first mode: the first fidelity threshold corresponds to afidelity of the first primary signal; and wherein in the second mode:the second fidelity threshold corresponds to a fidelity of the secondprimary signal.
 17. The mobile communication device of claim 14, whereinin the first mode: the fidelity of the first noise-reduced primarysignal corresponds to a signal-to-noise ratio (SNR) of the firstnoise-reduced primary signal; and wherein in the second mode: thefidelity of the second noise-reduced primary signal corresponds to anSNR of the second noise-reduced primary signal.
 18. The mobilecommunication device of claim 12, wherein the first sensor comprises oneor more first microphones and the second sensor comprises one or moresecond microphones.
 19. The mobile communication device of claim 1,wherein in the second mode, the camera is arranged and configured tocapture an image of the targeted source facing the camera, the imageassociated with the sound from the targeted source facing the camera.20. The method of claim 7, further comprising capturing, in the secondmode, an image of the targeted source facing the camera, the imageassociated with the sound from the targeted source facing the camera.